Process for producing crosslinked polyamides from lactams

ABSTRACT

Cross-linked polyamides are produced by the noncatalytic polymerization of a lactam and a bis-lactam. The polyamides have known utilities.

United States Patent Inventor Rene Marie-Joseph Roberts Charleston, W.Va.

Appl. No. 842,381

Filed July 16, 1969 Patented Dec. 7, 1971 Assignee Union CarbideCorporation New York, N.Y.

PROCESS FOR PRODUCING CROSSLINKED POLYAMIDES FROM LACTAMS 2 Claims, NoDrawings U.S. Cl 260/78 L Int. Cl C08g 20/10 Field of Search 260/78 LReferences Cited UNITED STATES PATENTS 4/l958 Munch et al FOREIGNPATENTS 6,606,079 ll/l967 Netherlands 260/78L OTHER REFERENCES ChemicalAbstracts, Vol. 68, No. l2, March l8, 1968, pg. 4895,QOIA5I PrimaryExaminer-Harold D. Anderson Assistant ExaminerL. M. PhynesAttorneys-Paul A. Rose, Louis C. Smith, Jr. and Francis M.

Fazio ABSTRACT: Cross-linked polyamides are produced by the noncatalyticpolymerization of a lactam and a bis-lactam. The polyamides have knownutilities.

PROCESS FOR PRODUCING CROSSLINKED POLYAMIDES FROM LACTAMS This inventionrelates to a noncatalytic method of producing cross-linked polyamidesfrom a lactam and a bis-lactam.

The catalytic polymerization of lactams is well-known. However, it hasnot heretofore been possible to polymerize a lactam in the absence of acatalyst, water or other additive. It has, consequently, been expectedthat bis-lactams would act in a similar manner.

It has now been found that a mixture of lactum and bis-lactam willpolymerize in the absence of catalyst or water. This find was completelyunexpected and unobvious.

The lactams are known, and those suitable for use in this invention arethe unsubstituted and substituted lactams of the formula:

Hfln-Hg wherein n has a value of from one to about 16 or more and thesubstituents can be alkyl, aryl, alkaryl, aralkyl, amino, carboxyl,cyano or any other group that will not unduly interfere with thepolymerization reaction.

Illustrative of the lactams which may be employed one can mentionbeta-propiolactam, gamma-butyrolactam, deltavalero-lactam,epsilon-caprolactam, laurolactam, stearolactam,N-methyl-epsilon-caprolactam, alpha-aminocaprolactam and the like.

Similarly the bis-lactams are known; these have the general formula:

Illustrative thereof one can mention bis(beta-propio-lactam),bis(gamma-butyrolactam), bis(delta-valerolactam), bis-(epsilon-caprolactam), bis-laurolactam, bis-stearolactam, bis( N-methyl-epsilon-caprolactam bis-alpha-aminocaprolactam), and the like.

In the process of this invention a mixture of lactam and bislactamcontaining about weight percent, or more, of the bis-lactam ispolymerized by heating in the absence of any appreciable amount of wateror catalyst. The bis-lactam can be as much as 90 percent of the reactionmixture. In the process a single lactam and bis-lactam can be used inthe reaction mixture to produce the polyamide copolymers or one can usetwo or more lactams and/or bis-lactams in the reaction.

The conventional methods for polymerizing a lactam to a polyamide can beused. These are well known and need not be described in detail here. Inthese methods, the reaction mixture is heated, preferably in an inertgas atmosphere to prevent undesired side reactions, at polycondensationtemperatures of from about 200 C. or less, to about 300 C. or more.

The polymers produced have better properties than the unmodifiedpolyamides heretofore obtained from the lactams. Further, theirstructural composition is different as established by differentialthermal analysis.

In a typical reaction 10 grams of epsilon-caprolactam and l gram of7,7-bis(epsilon-caprolactam) were placed in a heavy walled tube. Thetube contents were purged with nitrogen for ten minutes and the tube wassealed. The tube was heated in an oil bath maintained at 250 C. for sixhours. It was then removed from the bath, cooled to room temperature andbroken open. The copolyamide was crushed, extracted with boilingdistilled water in a Soxhlet extractor for six hours and dried at 90 C.under vacuum (Copolyamide I). When an attempt was made to polymerizedepsilon-caprolactam alone, without any catalyst or water present, we didnot obtain any polymer.

For comparative purposes a polyamide was produced in the same mannerusing the same epsilon-caprolactam and water as the initiator butwithout 7,7-bis(epsilon-caprloactam) in the reaction mixture (PolyamideII).

The copolyamide (Copolyamide I) produced by the process of thisinvention did not dissolve when heated for 10 minutes at 90 C. inconcentrated sulfuric acid whereas, the compara tive polyamide(Polyamide II) dissolved readily. Further, differential thermal analysison the two samples showed no crystalline melting point for thecopolyamide and a sharp peak at 215 C. to 230 C. for the polyamidecomparative sample.

Similarly, copolyamides are produced from the following combinations oflactams and bis-lactams, the parenthetical figures are parts by weight.

Copolyamide Lactam Bis-lactam A epsilon-caprolactam bis(betu-propiulactam) (20 B epsilon caprolactam bis(epsilon (70)caprolaclum) l5) beta-propioluctam 15) C delta-valerolactam bis(delta-(60) valerolactam) (40) D laurolactam (75) bis-laurolactam (25) Estearoluctam (70) bis(epsilmr caproluctam) (30 F epsilon-caprolactambis-stearolactum (50) What is claimed is:

1. A noncatalytic method for producing cross linked copolyamides whichcomprises reacting a mixture of (i) a lactam of the formula:

O=CI [lH (CH7)nGHg and (ii) from 10 to weight percent of a bis-lactam ofthe formula:

O=(|JNH NH-(.IJ=O

, (CH )nOH-H (CH2)n at a polycondensation temperature of from about 200to about 300 C.; n being an integer having a value of 1 to about 16.

2. The method of claim 1 wherein the lactam is epsiloncaprolactam andthe bis-lactam is bis(epsilon-capolactam).

i t l l

2. The method of claim 1 wherein the lactam is epsilon-caprolactam andthe bis-lactam is bis(epsilon-capolactam).